The invention relates to sealing punctures in tissues of living bodies. The invention can be used, for example, when sealing punctures in the walls of arteries (such as following an angio or PTCA procedure) or other blood vessels. Background and various details of such techniques can be found in U.S. patent application Ser. No. 09/704,726 entitled xe2x80x9cSealing Device and Wound Closure Devicexe2x80x9d and filed on Nov. 3, 2000 by Dan Akerfeldt et al; U.S. Pat. No. 5,613,974 (Assigned to Perclose, Inc.); and U.S. Pat. No. 6,090,130 (assigned to Kensey Nash Corporation). The entire contents of this application and these two patents are incorporated herein by reference.
In the course of using sealing devices or anchors that are inserted into an artery, it is helpful to detect the position of the various components with respect to the arterial wall. If an introducer is positioned based on feeling, there is a risk that the introducer pops out from the artery, and it is almost impossible to reintroduce it in an easy way. Ideally, the seal or anchor is deployed as close to the puncture hole as possible. If the seal or anchor is deployed too deep in the artery, the risk increases that the seal or anchor will be caught upstream in the artery before being seated on the puncture hole and/or cause injury to the inside of the artery wall.
An introducer is normally 10-15 cm long, and during cauterization it is fully inserted. To seal the puncture hole, a seal needs to have a diameter larger than the introducer, e.g.  greater than 3 mm. To be properly seated to the inside of the artery hole, the seal needs to be even larger, otherwise the seal may be pulled out by mistake. The femoral artery inside diameter is normally 5-10 mm in humans, and it is difficult to increase the seal width to more than 5 mm because, if the seal width is bigger, it is difficult to fit the seal into the arterial lumen without affecting the circularity of the lumen too much. The length of the seal can however be increased to achieve high pull out strength.
The FemoSeal seal (described in Ser. No. 09/704,726) and Kensey Nash AngioSeal anchors described in U.S. Pat. No. 6,090,130) have a length of 10 mm, and consequently can get caught perpendicular in the 5-10 mm arterial lumen if the position and direction of the seal or anchor inserted in the artery are not guided. As discussed above, the seal or anchor can also be caught in an artery branch upstream. The AngioSeal technique employs an anchor that can move around in the artery as its inner member. The anchor does not perform a sealing function (and is not a xe2x80x9csealxe2x80x9d as this term is used in this patent specification) but instead anchors an outer member and the outer member performs the sealing function. The AngioSeal technique solves the problem of detecting the position of the various components relative to the vessel wall by detecting the vessel wall by introducing an indicator through the introducer. This is a tube that extends 3 cm distal of the introducer tip with a side hole positioned 1 mm distal from the introducer tip. By pulling the introducer back and forth, the tip can be positioned at a desired position from the vessel wall by looking at blood dripping out from the indicator. This can be done without losing the entrance into the artery. Then, the anchor can be deployed near the puncture hole, 1 cm upstream, and the risk of getting the anchor caught upstream is reduced.
A technique used by Perclose (described in U.S. Pat. No. 5,613,974) is similar in that a channel through the device, with a side hole, is provided to visually detect blood emerging from the device handle to indicate the device position within the artery.
The invention addresses and solves two problems which occur in the sealing of punctures in blood vessels. The first problem is to detect the arterial wall in order to position the introducer tip at the correct location inside the vessel.
A second problem is to confirm that an inner seal itself is correctly positioned and is performing its sealing function.
In preferred embodiments of the invention, the position of a distal end of an introducer assembly in tissue is determined using a pressure sensor. The pressure sensor is connected to the proximal end of the introducer assembly. The introducer assembly has a fluid path between its distal end and its proximal end. Measured blood pressure is outputted as an indication of the position of the distal end of the introducer assembly in the tissue. Proper positioning of an inner seal is confirmed by placing the introducer assembly such that its distal end is in tissue outside a puncture in a blood vessel wall and observing a characteristic of blood at the proximal end of the introducer assembly. In both techniques, a waveform of the blood pressure at the distal end of the introducer assembly may be displayed on a display to provide additional information to a surgeon as to the relative position of the components with respect to various tissues.
A pressure transducer is not needed to confirm that the puncture is sealed, since the flow of blood can be observed from an output port in the introducer if the puncture is not sealed. The output port can be, for example, a hole in the proximal end of the introducer, a clear tube connected to the proximal end of the introducer, or the like. However, providing a pressure transducer, or a similar device, allows generation of pressure waveforms and thus provides additional information to the surgeon.